1. Technical Field
This invention relates generally to power adaptor for a portable electronic device that is mechanically structured so as to fit in the cigarette lighter of a vehicle, and more specifically to a cigarette lighter adaptor having a moveable, mechanical stepper joint to allow movement between the dongle and handle of the cigarette lighter adaptor.
2. Background Art
Many modern vehicles are provided with cigarette/cigar lighters. The lighter usually comprises a circular, socket aperture with a removable lighter cap. When actuated, electrical current flows through a high resistance element in the lighter cap, thereby causing the element to glow red-hot. A cigarette or cigar can then be ignited from the glowing metal.
The lighter socket can also be used to power a large range of portable appliances, for example, mobile phones, car vacuum cleaners, lap-top computers, televisions, chiller cabinets, etc. Recently, the sockets on their own (without the cigarette lighter cap) have been provided in cars, off road and other vehicles. Sockets without cigarette lighter caps are often labeled simply as xe2x80x9cpowerxe2x80x9d sockets. While some appliances are powered directly from the socket itself, others may require an adaptor.
The typical cigarette lighter adaptor has a dongle and a handle. The dongle is a plug member that is inserted into the vehicle lighter socket. The dongle is elongate with a first electrical contact at one end. The first electrical contact connects to a co-operating electrical contact at the base of the lighter socket. To ensure a good and reliable connection, it is preferable if the first electrical contact is mounted on the dongle such that the contact is resiliently biased towards the end of the dongle. In prior art adaptors, the first contact is electrically and mechanically connected to the remainder of the adapter via a spring. The dongle also includes a second electrical contact that is generally a pair of curved leaf springs that provide both an electrical connection and a mechanical friction force with/against the lighter socket.
Most prior art adaptors are manufactured in a single, rigid piece. Thus, the angle of the handlexe2x80x94the portion of the adaptor that couples to the portable electronic devicexe2x80x94is dependent upon the geometric orientation of the lighter socket. Some designers have attempted to add moveability to the handle (relative to the socket) by adding hinged members. For example, U.S. Pat. No. 6,478,628, issued to Ming, teaches an adaptor with a hinged dongle. The problem with adaptors like than in the ""628 patent is that their dongle-handle interface comprises a friction-based mechanical connection. In other words, the only thing that keeps the dongle at the proper angle relative to the handle is the friction applied by the handle material (usually plastic) against the dongle material (also usually plastic). After only a few dongle-handle angle adjustments, this joint can wear, thereby causing the handle to sag.
There is thus a need for an improved adaptor with a more robust handle-dongle interface.